Introduction
I bought the full Gustard Stack early this year, after long work of selection and long time spent reading the corresponding threads on head-fi as well as other sources.The stack is composed of the U12 (a USB interface), the X12 DAC and the H10 headphone amplifier.
Recently I upgraded the H10 with a full Burson V5-OPA-D / V5-OPA-S op-amp Kit. I used both the single "S" and the Dual "D" series of the OP-AMPs. A total of four pieces, to be clear.
TL;DR: An AMAZING upgrade for an already very good amplifier!
Associated Equipment, including Hardware and Software
Hardware
Dedicated Mini PC with Intel Atom D510 1.66GHz (dual core, Hyper Threading)Hardware: Supermicro X7SPA-H mainboard
Hardware: Linear PSU from italian brand ZetaGi (set @12V)
Hardware: 1x1GB + 1x2GB RAM
Software: Currently running Ubuntu Server 15.04, 64bit, Low Latency Kernel
Software: MPD (Music Player Daemon - http://www.musicpd.org)
Software: UPMPDCli (Upnp Renderer plugin for MPD - http://www.lesbonscomptes.com/upmpdcli/upmpdcli.html)
Gear
Schiit WyrdGustard U12 USB Interface
Gustard X12 DAC
Gustard H10 Headphone AMP
Burson V5-OPA-D
Burson V5-OPA-S
Additional software
Windows 7 desktop PC, used to run GMPC/Cantata as MPD clients and Linn Kinsky/Kazoo as UpNP control pointBubbleUpNP on Android as UpNP control point
Another Debian-based Linux box is dedicated to file sharing (via Samba and via MinimServer, a UpNP server)
Cables
USB Cables: Audioquest Cinnamon 0.75mHDMI Cable (I2S): Ricable HDMI Supreme F1
Balanced Cables: Neo By Oyaide D+ XLR
Headphones
Headphones: Sennheiser HD650; Sennheiser Momentum On Ear; Denon AH1001; Yamaha HP-3 (Orthodynamic, modded)The setup
All listening tests were made using the mentioned dedicated Linux box with mpd, either with the mediation of upmpdcli or natively.The Linux box also benefits of a Schiit Wyrd, which supposedly "cleans" the usb signal and has its own separated power supply, isolating the DAC from the noisy PC environment.
In my experience, the use of the Schiit Wyrd is very effective, altough the improvement is less evident when used before a dedicated interface like the Gustard U12. I consider the Schiit Wyrd one of my best audio purchases ever.
I find the Linux setup so clearly superior to the Windows counterpart that I do use the latter only occasionally: the Gustard X12 is connected via usb to the desktop PC, while the Gustard U12 is connected to the Linux box, with the Schiit Wyrd in the middle.
I also used upsampling @352.4kHz and @384kHz with sox, alternated with a more native configuration (a.k.a. bit perfect).
The Tracks
For this review, I mostly used the following tracks:Carlos Santana - 'Aqua Marine' from 'The Ultimate Collection'
Miles Davis - 'So What' from the 1959 album 'Kind of blue', purchased on HDTracks (24bit/192kHz)
Eric Clapton - 'Tears in Heaven', 'Running on Faith', 'Layla', and really most tracks from the 'Unplugged' album
Dire Straits - 'Money for nothing' and 'Brothers in Arms' from the omonimous album; 'Fade to Black', 'Planet of New Orleans', 'My Parties' from the album 'On Every Street'
Janine Jansen - 'Le quattro stagioni' (Antonio Vivaldi), purchased on HDTracks (24bit/96kHz)
Rebecca Pidgeon - '24 hours of love', 'Primitive Man' from the album 'The New York Girl's Club', also purchased on HDTracks (16bit/44.1kHz only, sadly)
Sting - 'Consider me gone', Moon over Bourbon street', 'Fortress around your heart' from the album 'The Dream of the Blue Turtles'; 'They dance alone', 'Little wing', 'History will teach us nothing' from the album '... Nothing like the sun'
Sting - 'A thousand years' from the album 'Brand New Day'.
All the tracks come from flac files ripped from my precious personal CD collection with Exact Audio Copy, except when otherwise noted (HDTracks downloads).
Of course other tracks were used, these being the most relevant ones.
The Listening
The H10 is currently my best headphone amp. I like it a lot. It has the power to drive my current headphones (the best being the Sennheiser HD650) effortlessly. It can also drive my vintage Yamaha HP-3 (orthodynamic) quite well.Before the H10, I was using the headphone output of the Yulong D200 DAC/Amp. Switching to the Gustard U12/X12/H10 has been a very relevant upgrade, in terms of both transparency of the DAC and output power of the amplifier.
My favourite albums now sound smooth and lush, and more dynamic than before. Also detail retrieval is on higher levels than with the Yulong D200 (a unit I still love though).
I never noticed any channel imbalance, even at low volumes.
The H10 is very equilibrate, not bright, but not even too dark.
The bass impact is notable but not bloated or muddy; instead, I would say it's precise and tight. Also, the bass response is tight even with low-impedance headphones like the Sennheiser Momentum On-Ear: those phones may sound quite muddy if the amplifier has high output impedance. For example, they don't sound good with the SMSL SAP-III, which in reality is targeted to high-impedance headphones only.
There is a good extension on higher frequencies (as far as I my hearing can sense) with no harshness.
Quite a nice amp though.
Then the Burson Op-Amps came in.
Here you can find some photos (already show on this post: http://www.head-fi.org/t/735828/gustard-h10-high-current-discrete-class-a-output-stage-headphone-amplifier/3450#post_12053024)
The installation has been very simple and straightforward.
So, what changed?
Well, pretty much everything, and for better!
The most obvious enhancements are, IMO, in clarity and smoothness. Details are not lost in this smoothness, and instead I actually noticed more details than with the stock op-amps.
Every track I played is now more 'live', more real and definitely more natural.
All the tracks from the album 'Unplugged' by Eric Clapton have never sounded so natural and detailed to my ears. Toe-tapping and the sense of rhythm is at its best.
The bass on the beginning of the track 'A thousand years' from Sting's album 'Brand New Day' is simply amazing now.
I realize how good the H10 sounds also by the fact I need less volume to enjoy good sound. This, IMO, indicates a clearly better clarity level given by the Burson Supreme V5 Op-Amp sets.
It's like having a completely new amp!!!
Don't get me wrong, I still think the H10 is a complete bargain. The thing is that with these op-amps it really reaches a new level.
The good thing is that you can start (relatively) cheap and upgrade it very easily.
Final thoughts
The H10 is a wonderful amplifier. It can drive pretty much every headphone, maybe with the exclusion of the Hifiman HE-6: anyway those headphones are on the extreme of the range.It will deliver hours of pleasure and will let you discover again your music collection. At a price lower than 400USD, it is really a no-brainer: I think you will not regret it.
With the Burson Supreme V5 Op-Amps, it becomes even better, under every possible aspect.
This amp has a good number of fans (myself included). You can find a dedicated thread on head-fi at this URL: http://www.head-fi.org/t/735828/gustard-h10-high-current-discrete-class-a-output-stage-headphone-amplifier
I bought a new dac also because the d200 nos happily lives on another system.
That said, the custard stack is superior IMO, but again the D200 is very good too.